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Edible Seaweed: Nutritious or Poisonous?

Edible sea vegetables including red, green and brown marine algae (aka seaweed) offer health benefits due to their concentrated vitamins, minerals, antioxidants, fiber and protein content. More commonly consumed in Asian, British and Caribbean cultures, most Americans consume seaweed as nori in sushi, wakame in seaweed salad, or unknowingly as a food additive including carageenan, kombu or agar.

Beyond nutrition, sea vegetables also benefit the environment and are used to clean polluted water. Referred to as extractive aquaculture or bioextraction, this sustainable cleaning process is promising for our environment but raises a question about human consumption of sea vegetables. If they are soaking up toxins and minerals from the water, what are we absorbing as we eat?

Not all seaweeds are created equal. Hijicki, also called Hiziki, is black algae that gained international attention as studies showed samples tested from around the world indicating high levels of arsenic and mercury. With more recent concern over arsenic in rice, the safety of some seaweed should also be considered.

The Canadian Food Inspection Agency (CFIA), Food Standards Agency (FSA) in Britain, Food and Environmental Hygiene Department (FEHD) of Hong Kong and New Zealand Food Safety Authority (NZFSA) have previously issued warnings against consumption of Hijicki based on toxic levels of arsenic found in some samples. A statement by Eden Foods in response to these warnings suggested that Hijicki can still be consumed in moderation as part of a healthy diet, but there are more recent studies on Korean men showing unsafe levels of arsenic and mercury coming from the diet they consume, high in sea vegetables. Here are the reports from CFIA and FSA.

It is important to understand that hijicki and other sea vegetables are nutritious foods if they are not contaminated. Limiting your intake of black hijicki if you don’t know the source is likely a best practice, though incorporating other types of edible sea vegetables can be beneficial. It is best to find a company that can ensure organic and sustainable seaweed fit for your consumption.

Eating sea vegetables can be part of a healthy diet and as they absorb toxins from the environment, so can they absorb toxins from our bodies while providing nourishing nutrients and vital minerals in concentrated and delicious way.
Here are some companies that test their sea vegetables

Ginger Hultin is a clinical dietitian specializing in integrative cancer care in Chicago, Illinois. She has a Masters degree in Nutrition from Bastyr University in Seattle and believes that whole foods and an emphasis on cooking at home can help overcome some of America’s food problems. Read her blog and follow her on twitter @GingerHultinRD